Yes, the two-mile thick ice sheets over north America abruptly melted then. Some suggest that it was a cosmic impact event that imparted the necessary energy to accomplish the meltdown. I think geologists have been unable to explain how solar energy alone was capable of developing the energy required to melt the ice sheets in the amount of time that it actually took. The climate change during the Younger Dryas was astonishing.
Actually, the ice age was ending around 15 to 18,000 years ago. then about 12 to 13,000 years ago, something big happened to the northern hemisphere. It may have wiped out the Clovis culture, killed most of the mega-fauna, created the Carolina Bays, and perhaps Lake Michigan. It also precipitated the Younger Dryas cold spell which lasted more than 1,000 years. Since the seas were lower as the ice age was ending, Florida was bigger with more land at a higher elevation.
Sunken Civ: Time to post that Firestone et al book which explains a lot of this. Thanks